Abstract
This study explores the application of Electron-Beam Welding (EBW) for joining Laser Powder-Bed-Fused Inconel 718 (L-PBF IN718) superalloy. Three different levels of electron beam speed and beam current were explored to give nine different electron beam heat inputs for experimentation. To define the weld characteristics microhardness, tensile, and fractography analysis using scanning electron microscopy, optical microscopy, and energy dispersive spectroscopy were conducted. Typical nail-shaped weld geometry was observed with penetration depth proportional to heat input. Most welded samples exceeded the yield strength (600MPa) and tensile strength (920MPa) requirements from the ASTM F3055 specifications for additively manufactured IN718, however, the specimens did not meet the ductility requirements (27%). Brittleness of the weld was attributed to the presence of brittle secondary phases in the weld matrix, and unfused metal powder of adjacent L-PBF layers. Post-processing heat treatments were recommended to improve the weld quality while improving the ductility of EBW joints.
Highlights
Additive manufacturing has exceeded from being a mere prototyping method to a method of production given its advantage in generating near-net-shaped parts with complex geometries
Similar published results were found for electron beam welding of rolled Inconel 718 (IN718) [10], [12], [15]
The L-PBF base metal revealed the presence of defects such as gas-filled spherical pores, and irregularly shaped voids on their surface concentrated on the boundaries of the printed samples
Summary
Additive manufacturing has exceeded from being a mere prototyping method to a method of production given its advantage in generating near-net-shaped parts with complex geometries. Powder-Bed-Fusion (L-PBF) process is additive manufacturing (AM) technique in which adjacent layers of fine metal powder are selectively fused with a powerful laser beam. Due to this layer-wise method of producing metal components and quality products, L-PBF has gained popularity in the aerospace, defence, energy, medical, and automotive industry. There is a need to explore an efficient way to join these parts reliably
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